IPython’s %edit magic command can open an editor of choice to edit
a code block.

The %edit command (and its alias %ed) will invoke the editor set in your
environment as EDITOR. If this variable is not set, it will default
to vi under Linux/Unix and to notepad under Windows. You may want to set this
variable properly and to a lightweight editor which doesn’t take too long to
start (that is, something other than a new instance of Emacs). This way you
can edit multi-line code quickly and with the power of a real editor right
inside IPython.

You can also control the editor by setting TerminalInteractiveShell.editor
in ipython_config.py.

If you are a dedicated Emacs user, and want to use Emacs when IPython’s
%edit magic command is called you should set up the Emacs server so that
new requests are handled by the original process. This means that almost no
time is spent in handling the request (assuming an Emacs process is already
running). For this to work, you need to set your EDITOR environment variable
to ‘emacsclient’. The code below, supplied by Francois Pinard, can then be
used in your .emacs file to enable the server:

Thanks to the work of Alexander Schmolck and Prabhu Ramachandran,
currently (X)Emacs and IPython get along very well in other ways.

Note

You will need to use a recent enough version of python-mode.el,
along with the file ipython.el. You can check that the version you
have of python-mode.el is new enough by either looking at the
revision number in the file itself, or asking for it in (X)Emacs via M-xpy-version. Versions 4.68 and newer contain the necessary fixes for
proper IPython support.

The file ipython.el is included with the IPython distribution, in the
directory docs/emacs. Once you put these files in your Emacs path, all
you need in your .emacs file is:

(require 'ipython)

This should give you full support for executing code snippets via
IPython, opening IPython as your Python shell via C-c!, etc.

You can customize the arguments passed to the IPython instance at startup by
setting the py-python-command-args variable. For example, to start always
with matplotlib integration and hardcoded light-background colors, you can use:

(setq py-python-command-args '("--matplotlib" "--colors" "LightBG"))

If you happen to get garbage instead of colored prompts as described in
the previous section, you may need to set also in your .emacs file:

(setq ansi-color-for-comint-mode t)

Notes on emacs support:

There is one caveat you should be aware of: you must start the IPython shell
before attempting to execute any code regions via C-c|. Simply type
C-c! to start IPython before passing any code regions to the
interpreter, and you shouldn’t experience any problems. This is due to a bug
in Python itself, which has been fixed for Python 2.3, but exists as of
Python 2.2.2 (reported as SF bug [ 737947 ]).

The (X)Emacs support is maintained by Alexander Schmolck, so all
comments/requests should be directed to him through the IPython mailing
lists.

This code is still somewhat experimental so it’s a bit rough around the
edges (although in practice, it works quite well).

Be aware that if you customized py-python-command previously, this value
will override what ipython.el does (because loading the customization
variables comes later).